Depression in Ontario: under-treatment and factors related to antidepressant use

Abstract

Our study examines how depression is treated in Ontario, with particular examination of the correlates of antidepressant utilization using a broad model of individual (clinical), demographic, and health system determinants of treatment. From a community epidemiologic survey, a sample of 333 individuals with major depression in the past year was identified. More than half received no treatment (untreated n=170, 51.1%), while 74 (22.2%) received treatment without medication, 29 (8.7%) received treatment mainly with anxiolytics, and only 60 (18.0%) were treated with antidepressants. All four groups had similar rates of alcohol and substance abuse. Disability and comorbid anxiety were common, with the least in the untreated group and the most in the antidepressant group. Increased use of antidepressants was associated with psychiatrist contact, while family physicians treated a substantial minority primarily with anxiolytics. Under a universal health care system, no differential access to antidepressants was found in terms of demographic characteristics. Clinical severity and contact with a psychiatrist correlate with antidepressant treatment of depression.

Introduction

Major depression is a highly prevalent disorder, with substantial morbidity and mortality (Weissman et al., 1988, Bland et al., 1988, Wells et al., 1989, Broadhead et al., 1990, Murphy, 1990, Blazer et al., 1994). Inspite of the powerful impact of depression on individuals and society, studies consistently reveal low rates of treatment of any type (Regier et al., 1988, Weissman et al., 1991, Eisenberg, 1992, Regier et al., 1993, Narrow et al., 1993). Antidepressant medications are the most studied and among the most effective forms of treatment, yet research has demonstrated that fewer than one in three currently depressed individuals who have started treatment take antidepressants (Wells et al., 1994). Many factors besides the simple presence of a diagnosis of major depression influence antidepressant use, particularly clincial characteristics such as severity, disability, and psychiatric co-morbidity, as well as provider or health system characteristics, and socio-demographic features. To improve the treatment of depression from a public health perspective, it is important to know how these factors relate to the use of antidepressants. Our study utilizes the Mental Health Supplement to the Ontario Health Survey to describe community patterns of treatment and identify features associated with antidepressant use.

Chief among the factors related to treatment are severity and disability. In general, individuals who report more disability and a greater severity of illness are more likely to seek services. (Bucholz and Robins, 1987, Bucholz and Dinwiddie, 1989, Dew et al., 1991, Olfson and Klerman, 1992b, Johnson et al., 1992, Du Fort et al., 1993, Kessler et al., 1994). The influence of co-morbidity on treatment outcome is clear: psychiatric co-morbidity has been associated with increased overall severity and poorer prognosis (O'Boyle and Hirschfeld, 1994, Wittchen, 1995), with the implication that these individuals are likely to need more comprehensive treatment (presumably including antidepressants). Health system and provider characteristics also shape treatment. Health system design can facilitate direct mental health treatment as well as referral to specialized services, as exemplified by the Canadian health care system (Bachrach, 1994, Kessler et al., 1997, Katz et al., 1997) or create economic barriers which lessen both the likelihood of any treatment and referral to the specialty mental health sector (Landeman et al., 1994, Rogers et al., 1993). Provider type, characterized either by specific professional (e.g. family physician vs. psychiatrist) or by health sector (e.g. general medical vs specialty mental health), influences treatment with results that suggest low rates and doses of antidepressant use in primary care settings (Johnson, 1974, Ketai and Hull, 1978, Wells et al., 1988, Katon et al., 1992), while treatment for depression by psychiatrists more often is associated with the use of antidepressants (Wells et al., 1994, Katon et al., 1992, Simon et al., 1993, Meredith et al., 1994), although not in all studies (Olfson and Klerman, 1992a).

Finally, demographic factors have long been understood to be significant predictors both of use of health services and of treatment. In a comprehensive literature review of outpatient mental health service use, Crow et al. (1994)identified gender, age, race, education, health status, and insurance coverage as significant predictors of use, while Rhodes and Goering (1994)particularly linked female gender to higher utilization. In a specific review of health care utilization related to depressive symptoms, two studies found that while the severity of depressive symptoms was the most powerful predictor of utilization, other significant predictors included age, race, and employment status (Dew et al., 1991, Olfson and Klerman, 1992a, Olfson and Klerman, 1992b). The effects of gender may extend even further: not only are women more likely to seek service, but several studies have demonstrated that women are more likely to explicitly discuss depressive and other psychiatric symptoms, which in turn would enhance the likelihood of appropriate treatment (Bucholz and Robins, 1987, Bucholz and Dinwiddie, 1989). Overall, the literature suggests that demographic factors would have a significant impact on the treatment of depression, with the suggestion that the treated sample would more likely be female, unemployed, and older. The fact that unemployment status has an impact on the likelihood of treatment and the unequivocal findings summarized by Crow and colleagues on the impact of health insurance status and likelihood of treatment underscores how individual characteristics and health system characteristics may be enmeshed, posing difficulties in understanding which factors are paramount. In our study, with all individuals covered by the same universal health care insurance, we have the opportunity to examine whether demographic factors such as income truly are correlated with treatment received, rather than `proxies' for identifying who might in fact lack adequate insurance. Nevertheless, such specific demographic factors may play a relatively small role when compared with key symptoms of the depressed individual (Dew et al., 1988, Dew et al., 1991, Olfson and Klerman, 1992b).

Effective treatment of depression, particularly with antidepressants, clearly reduces morbidity, mortality, and cost (Jonsson and Bebbington, 1994, Rapaport and Judd, 1995, Sturm and Wells, 1995). While not all individuals with major depression must be treated with medication (Thase, 1994), evaluation of the magnitude of antidepressant use and its correlates does provide a useful public health perspective on the treatment of depression. In order to determine which factors—individual (demographic and clinical), provider, and system (such as income when health insurance status is controlled)—are associated with antidepressant use, we examined the self-reported treatment received by a large sample of depressed individuals in the community. We hypothesized that the group of depressed individuals receiving antidepressants would: (1) constitute only a small fraction of the entire depressed sample, (2) be more likely to have seen psychiatrists, and (3) be more likely to be more severely ill as demonstrated by disability reporting and co-morbidity.